ABSTRACT
A b s t r a c t S t a n d a r d t e s t s o f a s p h a l t m i x t u r e s , t h e i r s t a b i l i t y , f l o w a a d b e h a v i o u r u n d e r s t a t i c l o a d does not g i v e t h e d e f o r m a t i o n c h a r a c t e r i s t i c s f o r c a l c u l a t i o n o f f l e x i b l e pavement permanent d e f o r m a t i o n a n d r u t d e p t h s . I n t h i s c o n t r i b u t i o n t h e r e a r e d e s c r i b e d two new d e v i c e s d e v e l o p e d a t R e s e a r c h I n s t i t u t e o f C i v i l E n g i n e e r i n g i n B r a t i s l a v a f o r t e s t i n g the r e s i s t e n c y o f a s p h a l t m i x t u r e s a g a i n s t the permanent d e f o r m a t i o n s * T h e r e a r e a p r i n c i p l e s o f method f o r c a l c u l a t i o n t h e permanent d e f o r m a t i o n on s u r f a c i n g o f f l e x i b l e pavement i n t h i s p a p e r a n d v a l u e s o f m a t e r i a l d e f o r m a t i o n c o e f f i c i e n t (K) as a c h a r a c t e r i s t i c o f a s p h a l t mixtures^ f o r permanent d e f o r m a t i o n c a l c u l a t i o n *
1 I n t r o d u c t i o n
I n the a n a l y t i c a l ( m e c h a n i s t i c ) d e s i g n method f o r f l e x i b l e pavements u s e d i n C z e c h o s l o v a k i a t h e r e i s a p p l i e d m a t h e m a t i c a l s o l u t i o n o f m u l t i l a y e r e l a s t i c h a l f - s p a c e f o r the a n a l y s i s o f s t r e s s e s a n d s t r a i n s o f pavement l a y e r s . Subgrade a n d bound as w e l l a s unbound l a y e r s a r e c h a r a c t e r i z e d by e l a s t i c i t y modulus B a n d P o i s s o n ' s r a t i o p. • These a r e c h a r a c t e r i s t i c s o f d e f o r m a t i o n m a t e r i a l p r o p e r t i e s dependent on l o a d i n g p a r t i c u l a r l y i t s i n t e n s i t y , d u r a t i o n a n d c y c l e s a n d on ambient c o n d i t i o n s ( m a i n l y t e m p e r a t u r e ) . I n t h e a n a l y s e s t h e r e a l v a l u e s o f d e f o r m a t i o n c h a r a c t e r i s t i c s need not be n e c e s s a r i l y u s e d , f o r t h i s a i m t h e r e can be u s e d the d e r i v e d d e s i g n v a l u e s . At t h e e v a u l a t i o n o f the d e s i g n e d pavement c o n s t r u c t i o n t h e r e a r e c o n s i d e r e d t h e b e n d i n g t e n s i l e s t r e s s i n bounded l a y e r s a n d c o m p r e s s i v e v e r t i c a l s t r e s s on t h e s u b g r a d e . A t p r e s e n t t ime we have s u p p l e m e n t e d t h e d e s i g n method f o r a s p h a l t pavements by t h e a n a l y s i s o f permanent d e f o r m a t i o n t h a t a p p e a r s i n f o r m o f r u t t i n g a t the pavement s u r f a c e . The b a s i c
assumptions for analysis of the permanent deformation of the multilayer asphalt pavement surface deformation is the possibility of summation of permanent deformation of separate payements layers and the subgrades
(1) where is permanent vertical deformation
- permanent deformation of the layer i , - permanent deformation of the layer i+1.
